In many instances, a pre-connectorized fiber optic cable, such as a trunk cable serving a data center in an office building, must be installed through a small diameter conduit or under a raised floor to satisfy space and aesthetic requirements. As used herein, the term “pre-connectorized fiber optic cable” refers to a communications cable including at least one optical fiber that is terminated to a fiber optic connector prior to installing the fiber optic cable at a service location, commonly referred to as a “customer premises.” Typically, the fiber optic cable is manufactured to a predetermined length and one or more optical fibers are terminated to respective fiber optic connectors in the factory (commonly referred to as “factory-connectorized”). However, the optical fibers may also be terminated to the respective fiber optic connectors at the customer premises (commonly referred to as “field-connectorized”) prior to installation of the fiber optic cable. In either case, the terminated end of the fiber optic cable and the fiber optic connectors must be protected during the installation. The current practice is to position the terminated end of the fiber optic cable and the fiber optic connectors within a protective housing, and to then pull the housing, connectors and cable through the conduit or under the raised floor using a conventional pulling sleeve having a pulling loop opposite the terminated end of the fiber optic cable. An existing pulling sleeve made of a mesh material and the use of the pulling sleeve to install a fiber optic cable is shown and described in recommended procedure documents SRP-009-026 Issue 2 entitled “Trunk Cable Pulling Sleeve” and SRP-009-027 Issue 3 entitled “SC-DC™ Trunk Cable Pulling Sleeve” published by Corning Cable Systems LLC of Hickory, N.C. Together, the protective housing and the pulling sleeve used to install a pre-connectorized fiber optic cable are known in the art, and referred to herein, as a “pulling grip.”
In an existing pulling grip, the protective housing consists of a flexible length of corrugated tubing that is placed over the connectors and secured to a furcation plug provided at the terminated end of the fiber optic cable. The pulling sleeve is then positioned over the corrugated tubing, secured to the furcation plug or the fiber optic cable, and advanced by hand through the conduit or under the raised floor using a rope attached to the pulling loop. Following installation of the fiber optic cable, the pulling sleeve and the corrugated tubing are disengaged and slid down the cable to expose the fiber optic connectors. The corrugated tubing, however, has a tendency to snag the connectors as it slides down the cable and thereby potentially damage the connectors and/or the respective optical fibers. Since they may be reused to reinstall the cable, the pulling sleeve and the corrugated tubing typically remain on the fiber optic cable following the initial installation, with the result that the pulling sleeve and the corrugated tubing take up a significant amount of the available volume under the raised floor. U.S. Pat. No. 5,863,083, assigned to the assignee of the present invention, describes an improved pulling grip that remedies the problems encountered with a protective housing consisting of corrugated tubing. The improved pulling grip includes a molded clamshell style pulling grip housing 6 having a plurality of slots 42 for temporarily retaining a plurality of fiber optic connectors 20 mounted on the ends of respective optical fibers 18 of a fiber optic cable 22. A pulling grip mesh 2 having a pulling loop 4 at one end is positioned over the pulling grip housing 6 with the fiber optic connectors 20 retained within the corresponding slots 42. The open end of the pulling grip mesh 2 is secured around a cable collar (furcation plug) 46 provided at the terminated end of the fiber optic cable 22 and a rope 3 is tied to the pulling loop 4 such that the pulling grip can be advanced by hand through a small diameter conduit or under a raised floor. Once the fiber optic cable 22 is installed in the desired location, the pulling grip mesh 2 is removed from the fiber optic cable 22 and the pulling grip housing 6 is opened to access the fiber optic connectors 20. Next, the fiber optic connectors 20 are removed from the slots 42 and the fiber optic cable 22 is removed from the pulling grip housing 6. Finally, the fiber optic connectors 20 are connected to the optical equipment utilized at the customer premises and strain relieved by securing the cable collar 46 to the communications hardware available at the customer premises, such as a distribution frame or rack, or a cross-connect housing mounted on a distribution frame or rack. As a result, the fiber optic connectors 20 are not snagged during removal of the pulling grip housing 6, and the reusable pulling grip mesh 2 and pulling grip housing 6 are not stored in the available volume under the raised floor.
While the improved pulling grip alleviates potential damage to the connectors and their respective optical fibers, and increases the available volume under the raised floor, it introduces different deficiencies. In particular, assembling the pulling grip housing 6, the cable collar 46 and the fiber optic connectors 20 is time consuming and labor intensive. The cable collar 46 at the terminated end of the fiber optic cable 22 is secured to the end of one of the internal compartments 24, 26 of the pulling grip housing 6 by cable ties 50 (FIG. 1), and the fiber optic connectors 20 must be loaded individually into respective ones of the slots 42 formed in one of the internal compartments 24, 26 (FIG. 6 and FIG. 10). Alternatively, one of the internal compartments 24, 26 of the pulling grip housing 6 could include an adhesive surface 70 for temporarily securing the fiber optic connectors 20 and the optical fibers 18. Regardless, securing the cable collar 46 on the internal compartments 24, 26 and routing the optical fibers 18 and the fiber optic connectors 20 individually into the slots 42 of the pulling grip housing 6 unnecessarily increases the time, and thus the cost, required to assemble the pulling grip. Furthermore, the fiber optic connectors 20 can work free of the slots 42 or the adhesive surface 70 inside the pulling grip housing 6 and potentially be damaged. In addition, the clamshell style pulling grip housing 6 is relatively costly to mold, particularly when the length of the pulling grip housing 6 is extended to accommodate a fiber optic cable 22 comprising a large number of optical fibers 18 terminated with fiber optic connectors 20. Further, the cable collar 46 at the terminated end of the fiber optic cable 22 is not readily integrated with the communications hardware typically found in a data center installation, and in particular, is not readily integrated with a conventional distribution frame or rack, or with a cross-connect housing mounted on a distribution frame or rack. For example, the diameter of the cable collar 46 varies significantly for different types of fiber optic cables and the exterior surface of the cable collar 46 does not provide a readily accessible mounting surface. Finally, the improved pulling grip continues to utilize the prior art pulling grip mesh 2 to advance the pulling grip housing 6, fiber optic connectors 20 and fiber optic cable 22 through the conduit or under the raised floor. However, the pulling grip mesh 2 tends to contract in the radial direction and thereby transfer a significant portion of the pulling load directly onto the pulling grip housing 6 instead of the cable collar 46, which is preferably strain relieved to the strength members of the fiber optic cable 22.
It is therefore apparent a pulling grip is needed that overcomes the problems encountered with a protective housing consisting of flexible corrugated tubing, yet does not lend itself to the deficiencies associated with a pulling grip comprising a molded clamshell style pulling grip housing and a conventional pulling grip mesh. In that regard, what is needed is a pulling grip that eliminates potential damage to the optical fibers and to the fiber optic connectors mounted upon the optical fibers, and does not take up any of the available volume under the raised floor of a data center. At the same time, loading the fiber optic connectors into the pulling grip should not be overly time consuming and labor intensive and the fiber optic connectors should be securely retained within the pulling grip housing during installation of the fiber optic cable. The pulling grip housing should also be cost effective to mold, even when its length is extended to accommodate a fiber optic cable comprising a large number of optical fibers terminated with fiber optic connectors. Furthermore, the terminated end of the fiber optic cable should be adapted to be readily integrated with the communications hardware typically found in a data center, such as a conventional distribution frame or rack, or a cross-connect housing mounted on a distribution frame or rack. Finally, the pulling grip should not utilize a conventional pulling grip mesh that contracts radially when pulled to advance the pulling grip housing, fiber optic connectors and fiber optic cable through a small diameter conduit or under a raised floor.